Developing countries are experiencing a rapid emergence of a new elite of super-rich individuals as their economies expand and mature.

A report published last week shows that the number of "high net-worth individuals" (HNWI) increased by 21% in South Korea, 19% in India and 17% in Russia over the past year. These dramatic increases in individual wealth were largely as a result of booming stock markets - the Dow Jones South Korea Index gained 55% in 2005, for example.

The World Wealth Report, published annually by the investment bank Merrill Lynch and the consult­ancy firm Capgemini, examines the spread of individuals around the world who have liquid assets of more than $1m, excluding their primary residence and consum­ables. At the end of 2005, it said, there were 8.7 million HNWIs worldwide - 6.5% more than a year before. Their wealth had grown by 8% to $33 trillion.

There was an even bigger jump in the number of "ultra high net-worth individuals" - those with financial assets of more than $30m. This club has 85,400 members world­wide, an increase of more than 10%. Together, these individuals, who represent 1% of the richest 1% in the world, control 24% of global wealth.

The growth in Britain's wealthy population was modest compared with the developing world. The number of HNWIs grew by 7% to just under 450,000, compared with a jump of nearly 9% in 2004. The authors of the report say this was probably because of a slowdown in the growth of the UK's gross domestic product (GDP) and a weaker stock market performance.

However, the rise in the number of rich individuals in Britain remained above the rate of GDP growth and compared well with that of other western European countries, reflecting the attractiveness of the UK as a home for the European rich. Overall in Europe there was a 4.5% increase in the number of HNWIs, compared with 6.8% in the US.

The report also suggests that the world's super-rich are starting to move their money out of the US. Although it remains the world's most popular region for investment, an increasing number of HNWIs are transferring assets to emerging ­markets such as Asia-Pacific and Latin America.

Jason McLean, one of the report's authors, said: "The world's wealth­iest individuals are not only becoming more sophisticated investors, they are also more determined than ever to achieve returns com­parable to those experienced in 2003 and 2004."

However, despite the continued growth in their numbers and wealth, the super-rich in the West are facing a crisis. As the baby-boomers, who make up a significant proportion of the world's wealthiest individuals, reach retirement age, they are having to work out how to pass on their wealth without being hit by inheritance taxes. According to the report, 61% of HNWIs around the world are over 56 years old, compared with just 15% of the world's population as a whole. This will soon create what the authors call "the largest wealth transfer in history".

"All HNWIs will have to review their inheritance plans," said Nick Tucker, the head of Merrill Lynch's UK private client business.